The present invention relates generally to control mechanisms and, more specifically, to a three-function control mechanism that employs a single control lever in order to actuate or move three separate actuators. The present invention is particularly applicable for use on a work vehicle, such as a bulldozer or loader, in order to actuate hydraulic cylinders that control the positioning of a blade or shovel carried by the work vehicle.
Many bulldozers and loaders are provided with elaborate control systems that allow an operator to adjust or change the position of the blade or shovel. Without limiting the applicability of the present invention to the control of a bulldozer blade, the invention will be described hereinafter in connection with a bulldozer, it being understood that the invention may be applicable to other work vehicles or other apparatus. Typically, the adjustments made by existing control systems to the bulldozer blade may include the following three movements: (1) raising and lowering of the blade; (2) the tilting of the blade about a first axis; or (3) angling of the blade about a second, mutually-perpendicular axis.
A typical bulldozer usually will have hydraulic cylinders that are coupled to the blade and that may be extended or retracted to change the position of the blade. The flow of hydraulic fluid to and from the hydraulic cylinders is typically controlled by corresponding valve systems that are actuated by movement of one or more control lever by the operator. Manipulation of more than one control lever in order to change the position of the blade can, however, be cumbersome to the operator. Furthermore, in one known control system where a single control lever is used, a significant number of parts are employed making the system relatively expensive to manufacture and assemble.
It is therefore desirable and an object of the present invention to provide a hydraulic control mechanism which features a single lever for actuating the valve systems. It is a further object of the present invention to provide a hydraulic control mechanism that is relatively uncomplicated having relatively few main parts and which can carry out each of the three functions (lift, tilt, and angle) independently or in unison.